1. Field of the Invention
The present invention relates generally to golf balls, including their structures and compositions. More particularly, the present invention relates to multi-layer golf balls having particular compositions, particularly compositions suitable for use for the mantle or intermediate layer of a golf ball, i.e., a layer positioned between the cover and the innermost core. According to preferred embodiments, the intermediate layer includes a quantity of glass, carbon, aramid, metallic, or other fibers.
Further, the present invention relates to mantle compositions which improve initial velocity, or distance, while maintaining or at least substantially maintaining spin and playability characteristics and, conversely, compositions which improve spin and playability characteristics, while maintaining or at least substantially maintaining initial velocity and distance.
2. Description of Background and Related Art
Modern golf balls generally include multiple layers, i.e., such as two-piece and three-piece balls, which include wound balls and balata-covered balls. Two-piece solid balls typically include a rubber single-piece spherical core and a hard ionomer resin thermoplastic cover. These balls provide a relatively high initial speed and, therefore, they perform optimally for drives and for shots with the long woods. However, such golf balls typically have a hard feel at impact, because of the rigidity of their covers, and their performance for short shots, such as those employed with the short irons, is less than optimal because of a relatively low spin rate.
Wound balls, which typically include a solid or liquid core around which is wound a tensioned elastic thread, covered with an outer layer of either an ionomer resin or balata or an elastomer blend, e.g., have a softer feel at impact and they have a relatively high spin rate. Although distance is sacrificed somewhat, with respect to the aforementioned two-piece balls, wound balls thus provide an improved playability, particularly for experienced players.
United Kingdom Patent Application No. 2 278 609 discloses a multi-layer golf ball which is intended to offer certain advantages of previously known balls employing ionomeric resins, these advantages including improved distance, without sacrificing other advantages of wound or multi-layer balls, such as playability. To that end, U.K. Patent Application No. 2 278 609 discloses a ball having an inner cover layer employing a high acid ionomer or ionomer blend and an outer layer employing a soft, very low modulus ionomer/ionomer blend, or a non-ionomeric thermoplastic elastomer.
Commonly owned U.S. Pat. No. 5,253,871 discloses a multi-layer golf ball intended to have a considerable initial speed, close to that of the faster balls, such as the two-piece balls mentioned above, for favorable performance for drives and shots with the long woods, while also having a good feel, enabling good control or playability during short iron play, such as that for the wound balls. To this end, U.S. Pat. No. 5,253,871 discloses a ball having an elastomeric core, a thermoplastic cover, and an intermediate thermoplastic layer composed of at least 10% by weight of amide block copolyether. As mentioned in U.S. Pat. No. 5,253,871, the remarkable property of amide block copolyether is that, in contrast with ionomeric resins, the lower the hardness and modulus, the higher becomes the impact resilience. Like the ionomer resins, the amide block copolyethers are available in a wide range of hardness and flex modulii. U.S. Pat. No. 5,253,871 also discloses the optional addition of an ionomer to the ether block copolymer composition so as to limit the deformation of the ball at impact, while maintaining the hardness of the composition.
The intermediate layer, or mantle, of the ball of U.S. Pat. No. 5,253,871 is protected from cutting and peeling by the cover to provide the ball with a good durability. A relatively wide choice of materials is disclosed for the cover. Among the preferred materials are cited ionomers, amide block copolyiners of the type used for the mantle but with greater hardness, ionomer and amide block copolymer compounds, thermoplastic polyurethanes, as well as combinations of these materials.
At the time of U.S. Pat. No. 5,253,871, the high acid ionomers were not publicly known. However, commonly owned U.S. application Ser. No. 09/136,845, filed on Aug. 20, 1998, the disclosure of which is incorporated by reference herein in its entirety, proposes a new composition for a cover that includes a soft amide block copolymer and a harder ionomer, such as a high acid ionomer. The cover composition has been found to contribute to the achievement of high values of spin rate for a better control, to improve the feel of the ball and, further, the cover composition has been found to contribute to the achievement of an increase in the initial speed and distance of the ball. The cover is disclosed as pertaining to all types of golf balls, including two-piece balls, three-piece solid balls, and wound balls.
Still further, commonly owned U.S. Provisional Application No. 60/070,497, filed on Jan. 5, 1998, the disclosure of which is also incorporated by reference herein in its entirety, discloses a composition for improving the durability of balls constructed according to U.S. application Ser. No. 08/915,081. Specifically, an agent for the compatibilization of the polyamide elastomer and the ionomer in the composition is described for reducing the incidence of cryogenic fractures and delamination at the interface between the ionomer and the polyamide elastomer.
Although golf balls employing various constructions and compositions are presently known, the initial speed and, therefore, the distance achieved with such golf balls tends to be limited if the spin rate and, thereby, the playability of such balls are not to be negatively affected. Similarly, spin rate and playability characteristics of golf balls tend to be limited if initial speed and distance are not to be negatively affected by other constructions and compositions.